noun
1
BAD : If you have luck, you'll be able to hear Carreras sing.
GOOD : If you're lucky, you'll be able to hear Carreras sing.
GOOD : If you're in luck, you'll be able to hear Carreras sing.
BAD : That afternoon she had luck and found the keys at the bottom of a drawer.
GOOD : That afternoon she was lucky and found the keys at the bottom of a drawer.
GOOD : That afternoon she had a stroke of luck and found the keys at the bottom of a drawer.
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be lucky, be in luck, (have) a stroke/bit of luck (NOT have luck ): 'We're lucky the coach didn't go without us.' 'You're in luck, there are still a few tickets left.' 'I'm so pleased she got the job. It's about time she had a bit of luck.'
Note that when luck is used with have , it is always modified: 'I've had enough bad luck to last me a lifetime.' 'Some people have all the luck.' 'He hasn't had much luck recently.'
2
BAD : I'd just like to say goodbye and wish you a good luck.
GOOD : I'd just like to say goodbye and wish you good luck.
BAD : What a rotten luck! There he was again, sitting right beside me.
GOOD : What rotten luck! There he was again, sitting right beside me.
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Luck is an uncountable noun: 'She's had a lot of bad luck recently.' 'Meeting the right partner is just a matter of luck.'